ftracer

A toolkit for tracing C/C++ program(including multi-thread program), it can generate a call graph for you
Sometimes you may hard to understand a complex program, especially a very big application. So you need a powerful tool to help you to dump the call graph.

Before you start

Please note that, the tracer works for you in the following scenarios:

• You can touch the source code, and can easy to re-compile it in your environment
• You need a time-line based call graph

If NOT, please leave.

Exceptions

• Your program have core dump issue, it may not help you, currently you should use gdb to fix it first

How to Use it

Check out

git clone [email protected]:finaldie/ftracer.git

Compile ftracer

make

Re-Compile your program

To make the tracer working, you should re-compile your application with -g -finstrument-functions flags

make CFLAGS="-g -finstrument-functions -O0"

NOTE: Make sure there is no optimization option like -O2, if exist, replace it with -O0 or just drop it. Btw, you can try the example in ftracer

Generate Call Graph Report

• PRELOAD ftracer.so in the wrapper script

  bash $ cat run.sh
  #!/bin/sh
  export LD_PRELOAD=/path/to/ftracer.so
  
  ./yourapp

• Run it

  ./run.sh

• Generate the Report

  cd tools
  ./gen_report.sh -e yourapp -f /tmp/trace.txt

Advanced

env variables

• Start tracer when enter in your specific function address

  export FTRACER_FUNC_ENTRY=xxx  # xxx is the function address, like 0000123
  

• Start tracer when receive your specific signal

  export FTRACER_SIG_NUM=10 # 10 is SIGUSR1, kill -s SIGUSR1 PID to start tracer
  

• Specific a output tracer file

  export FTRACER_FILE=/tmp/your_tracer_file
  

NOTE: About signal and function address entrance two features, they can not enable in the same time, if that, the signal feature will not be take effect.

gen_report Options

Sometimes, we deal with C++ program, there are a lot of noise in there, like std, boost... so we should filter them out

• -s Regex Symbol Filter

  For this, you should use -s arg, for example:

  gen_report.sh -e app -f /tmp/trace.txt -s "^std::"
  

• -S Filter by file/path

  For this, the -S arg will help you, for example if you want to filter all the c++ related information out, you should:

  gen_report.sh -e app -f /tmp/trace.txt -S /include/c++
  

• -p Keep at most N level of path

  If a path is too long, it will be a noise for us, so the -p parameter will help to keep at most N level of path, for example, there is a path /path/a/b/c/d.c, use -p 1 the path in the report will be c/d.c.
  If no -p or -p value is a negative number, this feature will be ignore

• -o Specific output folder

  The default output folder is /tmp, but if you want to specific another folder, -o output will help you.

• -d Don't cleanup the temporay data

  If you get wrong data when you run gen_report.sh, the temporay data will help you to debug what's happened, so if you want to debug it, pass the -d paramter.

• -v Show debug info

  If you need more information during the report generating, you can pass -v in

• -t Start N process to generate report

  The addr2line is slow, sometimes you need to start N process to generate the report in parallel, it will reduce the generating time. For example -t 4

• -F output format

  Default output format is plain, and you also can specific html format, for example -F html, this will be great help when you are dealing with a very big call graph.

Enjoy and Analysis the Report

For now, open the /tmp/trace_report.txt.threadid and enjoy it. The example like:

 1x main(/home/username/github/ftracer/example/test.c:44) - (called from ??:0)
.. 3x a(/home/username/github/ftracer/example/test.c:36) - (called from test.c:45)
.... 1x b(/home/username/github/ftracer/example/test.c:21) - (called from test.c:39)
...... 1x c(/home/username/github/ftracer/example/test.c:16) - (called from test.c:25)
.... 1x b(/home/username/github/ftracer/example/test.c:21) - (called from test.c:39)
...... 2x d(/home/username/github/ftracer/example/test.c:11) - (called from test.c:27)
...... 1x e(/home/username/github/ftracer/example/test.c:6) - (called from test.c:31)

More detail see the example